Adjustable limit control for tractor lift shafts



p ,1951 REE. STUTZKE 2,566,779 I ADJUSTABLE LIMIT CONTROL FOR TRACTOR LIFT SHAFTS Filed Nov'. 29, 1946] s sheets shet 1 fitter way Sept. 4, 1951 R. E. STUTZKE 2,566,779

ADJUSTABLE LIMIT CONTROL FOR TRACTOR LIFT SHAFTS 3 Sheets-Sheet 2 Filed NOV. 29, 1946 h: leranca mnvemenf Inventor:

fiober/ Sill/Ike per MW Attorney Sept. 4', 1951 R. E. STUTZKE ADJUSTABLE LIMIT CONTROL FOR TRACTOR L'IFT SHAFTS Filed Nov. 29, 1946 1 Full Refraction 5 Sheets-Sheet 5 bwerzior:

Attorney Patented Sept. 1, 1951 UNITED STATES PATENT OFFICE ADJUSTABLE LIMIT CONTROL FOR TRACTOR LIFT SHAFTS Robert E. Stutzke, Louisville, Ky., assignor to B. F. Avery & Sons Company, Louisville, Ky., a

corporation of Delaware Application November 29. 1946, Serial No. 713,052

19 Claims.

Farm tractors are commonly provided with power operated lift" shafts which may be angularly extended and retracted over a predetermined working angle to lower and raise the ground working tools of certain tractor drawn implements such as rakes, mowers, plows and the like or to angle and straighten the ground working tools of other tractor drawn implements such as disc narrows. To effect a power operation of the lift shaft, tractors are conventionally equipped with a double acting hydraulic power unit for extending and retracting the shaft; a continuously operating engine-driven pump for energizing the power unit; a normally closed reversible valve controlling the pump connection to the power unit; a manually operable valve rod for operating the valve in one direction from off to on to extend the shaft and in .the opposite direction from off to on to retract the shaft; and spring means yieldably urging the valve rod toward and normally holding it in the valve closed position.

' It is desirable to provide a control mechanism for latching the valve rod in each of its on positions and for automatically unlatching it to stop the lift shaft in its fully retracted position and in any of a number of predetermined extended positions ranging from a desired mini-- Conventional structure of Fig. 1

As indicated above, Fig. 1 shows the control mechanism mounted on a tractor and operatively connected to the various other parts inshaft 3 and connected by a link 5 to a double acting hydraulic power unit 6, which is energized by a pump 1; a tractor engine 8 operatively connected to drive the pump continuously so long as the engine is running; a normally closed reversible valve 9 controlling the pump connection to the power unit; and a manually operable valve rod Ill for operating the normally mum degree of partial extension to full extension. Such forms the principal object of the present invention.

Another object of the invention is to provide 'a control mechanism which operates to stop the shaft in its fully retracted position and which may be easily and quickly adjusted to stop the shaft in any predetermined extended positions ranging from partial to full extension.

A further object of the invention'is to provide a control mechanism which is inexpensive to construct, simple to operate and reliable in operation.

An embodiment of the invention is illustrated in the accompanying drawing wherein:

Fig. 1 is a perspective view of an embodiment of my invention applied to a tractor, this view showing the relation of the control mechanism to the control mechanism to the other parts involved in its operation;

Fig. 2 is a longitudinal vertical section through one-half of the control mechanism;

Fig. 3 is a similar section through the other half thereof; and

Figs. 4-11 are schematic views of the control mechanism at various stages of its operation.

closed valve from off to "on in one direction (see arrow E) to a shaft extending position and from off to on in the opposite or reverse direction (see arrow R) to a shaft retracting position. The power unit illustrated is of a conventional type which not only encloses the body of the the valve 9 but also conceals the spring means which yieldably urges the valve rod toward, and normally holds it in, the valve closed or 01f position.

Control mechanism of Figs. 2 and 3 Speaking generally a control mechanism constructed in accordance with my invention ineludes: (a) means for movably supporting the valve rod Ill on the tractor; (b) a latch mechanism for releasably holding the valve rod in either of its operating positions; (0) arlimit arm connected to the lift shaft for angular extension and retraction movement in the path extending along the valve rod in; (d) a retraction stop fixedly mounted on the valve rod in a position such that, when the rod is retracted to and latched in its retracted position, the stop will be correspondingly retracted to a setting in the retraction path of the limit arm where it will ultimately be engaged by the retracting limit arm and moved sufficiently to unlatch the valve rod in time to stop the shaft in its fully retracted position; and (e) an extension stop adjustably mounted on the valve rod In in a position such that, when the rod is extended to and latched in its extended position, the extension stop will be correspondingly extended to a setting in the extension path of the limit arm where it will ulti-' mately be engaged by the extending limit arm and moved sufficiently to unlatch the valve rod in time to stop the shaft in an extended position corresponding to the setting of the extension stop.

The means for v nrovably supporting the valve rod It! on the tractor includes a casing llw in which the valve rod is slidably mounted intermediate its ends, the casing has bearing seats l2 and I3, at 61 afli t erit its opposite ends, on which the valve rod is slidabl supported. .A I

The latch mechanism for the valve rod is located at the bearing seat l3 of easing II. It includes: a spring pressed ball HI nropntegl in the bearing seat; and an elongate collar fixedly mounted on the rod for movement therewithgaxr ially along the bearing seat. The collar has a centrany dispose ttes l n e.c i.vinstth ball to latch the rod in the valve closed position and recesses E and Rf; w ioh are' disposed equidistantly from opposite sides" of the central recesses. for receiving the ball to latclr the rod in" the shaft extending and retracting positions respectively. Only a small horiaontal movement of the valve rod is necessary to raise the ball vertically out of either recess Ei or R ariid thus unlatch the'rod. A e this. mall fl i i m m the valve spring moves th valve rod to the off position with 91 5 13? .39 ,2 fi -his latter movement is herein" designated as the snap travel of am-T :7 n l The limit arm; whioh is cqnneetedto the lift shaft for angular extensionoandretraction ina 3 path extend n a flflgl h r rei q'd t 'qq an arm l6 pivotally mou 4 ed adjacent the bottom of the casing II to project from t pivot both downwardly out of the casing and-upwardly through the casing; Tlfre dowriwaiidly projecting end of the limitarm lfi is oonfreot'ed through a link I! to an extension pfthe crank m 4 on the lift shaft. when the f rm shaft is angularly extended or retracted, the upperportion of the limit arm, whichis ran ed to exte nd both sides of the valverod'; will do I w pon ngly extended and retracted ove a p oet jim neupath extending along the valuve rod I: one prong of the upper end of th lilliilt gil'njf [It projects through a slot l8 in the top of the'cas'ing ll: Tlhecasing is provided with graduations l9 spaced along this Slot and, o d p fi stha nera l 9.? th trantor, a readily visible indication of the lift shaft pos'ition; I

The manneri ms-may e any suitable member fixedly mounted on the valve rod-I 0. In the present case, the left end 2| of the" latching collar l5 functions as a retraction stop; 'When the valve rod is retracted to and latched in its retracted position; the retraction stop 2| will be simultaneously and corresp'ondingly retracted to and held in a retracted positionin the retraction path of the limit arm I 6; this"position being indicated in dotted lines in 'Fig. 3. In this position, it will be engaged by the retracting limit arm l6 when the retracting lift shaft 3 and the limit arm I6 each reach a position slightly in advance of its fully retracted position. As the lift shaft, and limit arm continue on to their respective fully retracted positions, the limit arm will move the rod from itsretractedposition over the small distance required to unlat'ch it, and the valve'will then snap the rod to itsofi position, both of these operations occuring'in time to stop the lift shaft in its fully retracted position.

An extension stop my be provided by any ll being fixedly mounted on one of the brackets 2 ,The casing si on stop is in its off position for a given exa d t .s 'i: re t t e i ii n than into abl m ns r n.

tension setting. In such ofi position, the extentop is pi'bperly spaced from its extended position: for the given extension setting, by a distance equal to the full extension travel of the .-ro d i. e. theltrfeiigil it undergoes during its unextension step inust besetby guess unless gr are provi for visu quired for desired degrees of extension. But

even with graduatioiis the manual adjustment still requires bothersome visual observancfl and adjustment time. I t is@desirable therefora to provide a simple arrangen e t wliich witli lit e er 0 Q l QP-LQW eas l n qu kl 9'- or less automaticallyat any desired point within the necessary ra r i ihe, se imtnfiw fiflize a sxtelh 129 m nt d 9 thslrg rs r "l! e e u ime t along, ands swi rm gt 20' the r t in t a ng of p si misj h h s requ d. t S op the lift shaftw'ithin its desired range or partial to full extension. and permits automatic resett o e, x ri s c St whe t 1 d. s t off position wit nl' ll, 1ift sliarftand limit arm in the position of newly desired extension. Automa r se s vwas9 m, she it i acc'q da ce w the present invention by the provision ofresili6 1? m n hi W .e .1.= 1?@w ?s l from the rod; opera te automatically to move the extension stop along the rod to a ,pos"ition wherein it is spacedr from the newly extended position of the limit arm y a distanceequal to the snap vtension stop,,n echanism of this invention comprises: an extension stop of the character Stated; steerin vI m 4.5.. for. rs as blr st e in t xe to the ro l ,in anyof its operative settings; yielda c, eg q i t and normallyelongate compressib 'anged between the stop and limit for lineal movement with thereleas'd stop for cornpressing movement remnants I th secured stop, said elongate means 0 mg compressible over a distance equal to the'sna'p travel of the rod from its normally elongate position to a compressed position in which "it positively engages the stop; said yieldahle 'and coir'i-pre ssible means being cooperatively operable, when the limit arm is in a position of newly desiredextension and the rod is in its ofi position, to move allrn n i t hs'mthe app qpria e iiiiijimiem eand the free end thereof. The securing means comprises a screw 23 for releasably securing the extension stop 22 to the valve rod HI. In the embodiment shown the screw 23 releasably secures the stop 22 to an end sleeve 24 into which the stop projects. The end sleeve 24 encloses the free end of the rod and is rigidly secured thereto by a pin 25.

The yieldable means comprises an urging spring 26 positioned within the end sleeve 24 to encircle the rod between the adjacent end of the stop 22 and an opposed wall of the end sleeve 24. In Fig. 2 the urging spring 26 is shown in its fully expanded condition which corresponds to the least extension of the lift shaft and the limit arm.

The elongate compressible means comprises a spring 21 encircling the valve rod l between the stop 22 and the limit arm, shown in its fully expanded position in Figure 2. The compressible spring 21 is enclosed within a cylinder 28 between washers 29 at opposite ends of the cylinder, and the limit arm end of the cylinder has a collar to serving as an abutment for engagement by the limit arm. When collar 30 is engaged by the limit arm in moving toward the left the spring 21 provides a yielding lost motion and is compressed between one washer 29 engaging sleeve 22 and the other washer 29 at the limit arm end of the cylinder. However, a pair of lips 3| prevent the spring 21 forcing the adjacent washer 29 outof the cylinder.

Operation see Figs. 4-11 The operation of the extension stop mechanism may be readily explained by reference to the schematic views shown in Figs. 4-11, wherein the full extension travel of arm I6 is assumed to be substantially equal to the snap travel of the valve rod although ordinarily it will be much greater.

Fig. 4 shows the valve rod In in its off position, the limit arm IS in its fully retracted position and the extension stop 22 in the position on valve rod 10 when it is set to stop the lift shaft ,at its fully extended position.

Fig. 5 shows the parts as theyappear when the valve rod and extension stop have been moved to the shaft extending position but before move- .ment of the limit arm in the direction indicated :by the arrow has begun. In this position, it will be noted that the abutment 30 has been moved with the valve rod and engages the limit arm,

and the spring 21 is substantially non-compressed.

Fig. 6 simply shows the parts as they appear :during the ensuing extension movement when to unlatch the rod from'the ball [4.

Fig. 8 shows the parts as they appear when ..;.the rod returns toits -ofl position; =Here again 6 it will be noted that the elongate compressible means has returned to its fully expanded position in which it engages the fully extended limit arm.

Fig. 9 shows the parts as they appear when the rod ID is moved from the off position to its shaft retracting position but before the retracting movement of the. limit are in the direction shown has begun.

Fig. 10 shows the parts as they appear when the limit arm has reached a position of partial retraction in its movement toward the retraction stop. It will be understood that the limit arm will continue to retract until it strikes the stop 2| and unlatches the rod l0.

Fig. 11 illustrates the mechanism after it has been reset to stop the lift shaft automatically at a point of midway extension. To effect the necessary change in the setting of the stop 22 from the full extension setting shown in Figs. 4-10,

the valve rod is manually retracted from its off position in Fig. 8 to its retracted position in Fig. 9 to initiate the retraction of the lift shaft. When the lift shaft reaches a position of half way extension, the valve rod is manually pushed out of its retracted position and returned to the oif position. The extension arm l6 and control rod It! now will be in the position shown in Figure 11, but extension stop 22 will be in the relative position shown in Figure 4, and the limit arm will be spaced from the elongate compressible means 28 a distance equal to the distance between the fully extended and half way extended positions of the limit arm. Automatic reset is now accomplished simply by releasing the screw 23 momentarily. During momentary release, the urging spring expands from .its relatively compressed position shown in Fig. 4 to the less compressed position shown in Fig. 11 and, in expanding, it moves the extension stop 22 and the elongate compressible means toward and into engagement with the limilt arm as shown in Fig. 11 whereupon it is only necessary to retighten the screw 23 to hold the extension stopin its new setting. The urging spring 25 does not compress the spring 21; hence in the new setting, when the control rod I0 is moved to the position shown in Figure 5 to initiate extension of the shaft, the compressible means in the extension stop is compressed so that only a slight movement of arm I6, is sufficient to move the ball I4 out of the detent to allow the valve rod to snap to off position. When thus adjusted, the operator need only move the rod from its off position to its retracted position to retract the limit arm and stop it automatically in its fully retracted position. Now, when the operator moves the control rod from its off position to its extended position, the limit arm moves to the left and by the time it reaches the halfway position spring 21 has been fully compressedso that only a slight further movement is required to raise the ball [4 out of its groove to permit the control rod to close the valve and thus automatically stop the shaft in a position of half way extension.

Having described my invention, I claim:

1. In a control mechanism for a tractor lift motor reversing valve having an intermediate off tioning member in adjusted positiom'resilient -.-;=ga e.d ysa :l m justably carried -on; ;s aid rod; an adapted to be engaged by said limita .mpand I i st e the position a secon isionv 9.. .In a. ontr01-.-.m ohan m r atract s izmotor r v si walveshavine.ea ensi n e dl :traction positions.-,. .and an intermediate stop, pois t av valve ontrol :rD a.dapt. cl.-.t escon- 1: neoted .to. ;said: valve detenta means t seleotiyiely;

means :between.-;said second abutment a d p si- :tioning member providing a 1051; motion co n .nectio'n; andresilient means :biasin :Said positioning member toward said limit arm.

2. A control mechanism as iSllQQifiG- i e a ml having detent means :yieldably 1 holding said 991%- trol rod in intermediate. and extreme. a-PQSMQHS- 3. In a control mechanism ,for :a tractor .f;t :motors. reversing .valve :having andntermediate off position: a limit armadapted .jto bemoved by :srotatable shaft between two extreme po it on .a. valve. :control :rod .havingan abutment (6 32. 9 :gadapted .tdbe, engaged-.zbysaid limitgarm adj 423 one extreme position; asecondzabntment on said anode-adapted jco;.-;be;engaeedhysaidglimit arm ad- 3 :iaeentthe other .zextneme. position thereof 3 means zforaloeking saidgsecond gaioutment on said-rod at 131113:dj t' pfl i on toner-y theen agiine-n tion 10f saidliinitvarm and attenahut nent and. means ,biasi-n .saiaseeondmbotment t we 'i fi m-- 4.2In a controLmechani-sm for ar-tractor Jift .motor reversing valve-: 1 vz i pi interme t eofi position .1- a. limit-arms dallt d 5L .1 i ed-b v a .--.rotatable shaft between .two ex r m -.I Q 12 .-.a valve.controlnrod'having. an; abutment thereon adapted to beengaeed by.saidlii ita madiac n gone. extremeposition pa; spring abutment on said -;rod; ..a springgengagingysaid abutment; a sleeve .islidable .on said; shaft .engagm 1.53 1 p n a one. end and-,iproviding-an. abutmentatthe other .qend-adapted.toibeiengased bma dlim m ad- .jacent the other extreme position thereof; and .means for. locking said-sleev onsaid mdata 'Ladjustedposition. to vary; the engaging position .ilof said. limitearmland;.;1atter.abotment.

.'.-5.:A...control-meehanism. ass specified i l 4 :having means. biasing .said second abutment toward said limit arm.

, 69A controlrimechanism.as'speoif din fil im 5 .having. indexing. .means .to' indicate th DQ i Q -lof. said limit. arm.

1'7. In; a control. meohanism..for. a tractor lift motor reversing va1ve:.=.a-.1imit. armladapted, to .=bemoved .by'5 a rotatable shaft .between; two; ex- :treme :postions; avalye control; rod having an abutment sthereon adapted .to .be. engaeedbyzsaid .=limit1arm. adjaoentoneextreme. position; v.detent smeans .for yield-inglyiholdingsaid. control rod .in intermediate and=v extreme-;.=. positions; a sleeve iv'slidable 0n saictz-rod arsecond; abutment. movable :ewith said sleeve. and; .ad-apted; to-be, engaged-my said .Jimiti arm? in movementztowam the other .vtextremepositiom; a asecond. sleevepon said rod 1 having. a; telescoping-engagementwith the; first sleeve; a spring;in-.;said second:sleevegengaging I the first-sleeve; and means for.loekingsaidsleeves together.

- -8. Ina control mechanism-forge .tractorlift ;motor reversingiva-lve.havingiextension and retraction positions,- and an. intermediate stop position; a valvecontrol rod adapted toloe ooi'meoted to. said. valve means yieldingly retaining said rod. in intermediate :or. mend positions; a limit arm adapted to be operated by a rotatable snaft b tw xtended.and..;retr ted;.p si iqn stop on one side of ;-sa i limit-arm n ted to be enrm,-.;and ,eond stopadearns-stone sem nalseam n as $95 in iex ens on. or.

and adapted to be engaged BS said arm1 I said rod out o ret aeiien.i o the oppo te. sidenf 1 .3 m e abutment entl-y e. es i rl i o heies aeedt sa d-1.11mi mi not .out. of ext nsionpositjgnj n di j re ilientl ;oq n pasw; ei. .rod. Y

- 10. Ina qntro ime ean m .i9r',.a,. nazw g11; .motor1 Qlfl ii %lY bias dii a ofi position: a valve rod actuator tween tw extreme. no.5. .rod naririaan a i .sai dhval-ve. v

- l-iIn eombin t omw h. essence .troile.d...by a. reyersine .i diat p sitiontand motor .retraotioneodextension. po itions ofla tool..- aisin sen ;lowerin shaitoonnected. to; .ise .loscillated. thereby; a limit .arm connected tone..movedsbyisaidshaft; ay lye p ra in rod; .aniebutmentfionisaid rodepos .tioned. toabe; engaged by said; limit j arnradjagent one.extrementjitsmovement;:asecondabutmen .adjustably mountedson said. rodinno iti n tap engaged by. saidiimit. ammuponmovement in. th opposite direction; means. for. lockine saidasfew 0nd abutment adjusted .positioni iiiesilient means biasing said second abutment toward said limit arm; indexing means-sashes, the position member having an abutment ,tnereonp as b b as ng. member;

'13. In a between.,tvvo extreme positions m mper;hav1 g e5 asiitin v b' "a 1' m enup ment in on d eetion a se ind, 'bfitmen adjustably arried .,iiy.fsaid aitacgfi is. ee-

e a r i e e aid-.seeendebfimefit steer. .9 Qmi t ei sp etr i-m m m t ma si Said tro emb reop rah suponsreleasei or .zrsa 'ist p m a. s o..l in t-znovementof thasecond ml-abll me ins aiidireetion, away; .from ethealimit member; and spring means operable upon release of said releasable means for biasing said second abutment toward the limit member.

14. In a control mechanism for a tractor lift motor reversing valve having an intermediate off position: a limit arm adapted to be moved by a rotatable shaft between two extreme positions; a valve control rod biased to off position and having an abutment positioned thereon in position to be engaged by said limit arm adjacent one extreme position; a second abutment movable on said rod in position to be engaged by said limit arm adjacent the other extreme position thereof; a positioning member engaging said second abutment and movable along said rod to vary the engaging position of said limit arm and second abutment; resilient means between said rod and positioning member; and means for looking said positioning member on said rod.

15. In a control mechanism for a tractor lift motor reversing valve having an intermediate ofi position: a limit arm adapted to be moved by a-rotatable shaft between two extreme positions; a movable valve control rod biased to off position and having an abutment thereon located to be engaged by said limit arm adjacent one extreme position; a second abutment on said rozl located to be engaged by said limit arm adjacent the other extreme position thereof; detent means yieldably retaining said rod in oii' position; and means for locking said second abutment on said rod at an adjusted position to vary the engaging position of said limit arm and second abutment.

16. In a control mechanism for a tractor lift 7 motor reversing valve: a limit arm adapted to an adjustment member for said resilient means; 7

a second resilient means oppositely biasing said rod and adjustment member; and means releasably locking said rod and adjustment member against relative movement.

17. In a control mechanism for a tractor lift motor: a motor reversing valve member movable from a motor-off position to forward and reverse motor operating positions; a rod connected to said valve member for moving it from its ofi position to its motor operating positions, said rod having corresponding positions and being manually movable from a valve-ofi position forwardly to one operating position and backwardiy to the reverse operating position; detent means arranged to hold said rod and valve member yieldably in each operating position; a limit arm connected to be moved, by the motor, correspondingly back and forth between two extreme positions; and motor stopping means for each extremeposition of the arm, one stopping means being arranged on the forward side of the limit arm in position to be actuated by the arm, as it moves forwardly toward one of its extreme positions and the other stopping means being arranged on the backward side of the limit arm in position to be actuated by the arm, as it moves backwardly toward the other of its extreme positions, each of said stopping means being connected to the valve rod and operable when actuated to release the valve member and rod from the detent, which holds them in an operating position, so as to allow them to return to the ofi position.

18. The mechanism of claim 17 wherein: said limit arm is arranged for back-and-forth movement along the rod; and said arm and rod are so arranged that, when the rod is moved in one direction to one of its operating positions, the limit arm is then caused to move in the reverse direction; and said motor stopping means are mounted on the rod.

19. The mechanism of claim 18 wherein: one of said motor stop means is normally mounted on the rod at a position corresponding to one extreme position of the limit arm; and the other motor stop means is slidably mounted for movement along the rod to vary the location of the other extreme position of the limit arm; and means are provided for releasably locking the adjustable stop means to the rod at its adjusted position.

ROBERT E. STUTZKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 279,887 S-titzel June 19, 1883 1,667,138 Barks Apr. 24, 1928 2,286,256 Brown June 16, 1942 2,311,516 Brown Feb. 16, 1943 

